wc -l medals.txt
grep -E "中国|中国香港|中国台北" medals.txt | sort -k2nr
sort -t"," -k4nr medals.txt | head -n 5 | cut -d"," -f1
sort -t"," -k2nr medals.txt | head -n 5 ; sort -t"," -k2nr medals.txt |head -n 5| awk -F"," "{sum+=\$2} END{print sum}"
